Applicant has done extensive work with both Surface Effect Ship(s) (SES) in the form of his SEACOASTER SES designs and Air Lubricated Ship(s) (ALS). The SEACOASTER SES is seeing good success in the commercial area in the form of a high speed passenger ferry and is now the recipient of a government funded program to evaluate it for high speed navel vessels. He has run model tests on his ALS concepts.
The big difference between the SEACOASTER SES and the ALS is that the SEACOASTER SES, as is the case of other SESs, starts with the bow at or near the water surface and blower pressurized air then forces the level of the water inside of an air cavity in the underside of the SEACOASTER's hull down going from the bow to the stern. In the case of the ALS, the bow of the vessel is, at least in the main, lower than the air layer after a discontinuity such as a step in the bottom of the ALS forward of the air layer. The blower pressurized air layer then rises going from the forward discontinuity to the stern of the ALS.
Why the different approaches for the SES and the ALS? The SES is accepted as being more efficient from a hull resistance standpoint since it does not have the drag of the deeply submerged bow that the ALS has. However, the blower power required for the SES is considerably higher than for the ALS. The reason is that the air pressure in the SES's air cushion must physically force the water level down going from the bow to the stem. The ALS air layer requires only a small amount of makeup air since the bow forward of the air layer has already made a deep hole in the water. The SES therefore requires more blower power than the ALS. This is not a problem for the SES up to vessels of say 400-600 feet; however, at large sizes the blower power for the SES can equal the required propulsive power. For example, a 750 foot SES may require only half of the propulsive power of an equal size standard hull but it may require just as much power to run its blowers. A 750 foot ALS may offer a 25 percent efficiency gain compared to a standard hull but requires only five percent of propulsive power for its blowers. This gives the advantage to the ALS for the 750 footer.
Just to keep things in perspective, a 150 foot SES requires only about half of the propulsive power of a standard hull but it requires an additional 10-15 percent of the propulsive power to power its blowers. A similar size ALS would offer about a 20 percent reduction in propulsive power but would require only about five percent for its blower power. So the advantage goes to the SES here.
After all of this discussion, we now come to the instant invention. There has been some progress recently in the design and testing of Lifting Body Ships (LBS). However, they are not as efficient as the SES or the ALS. The main advantage show by the LBS is its extreme stability in rough seas.
The instant invention applies air lubrication to the underwater lifting body of the LBS. This makes for a much more efficient LBS especially at high speeds. Further, the instant invention can utilize propulsor water inlets that enhance the boundary layer characteristics over the top of the lifting body thereby increasing the efficiency of lift of the LBS's lifting body.